The present invention relates to a thin film forming apparatus and a thin film forming method and to a method for producing a thin film semiconductor device, more particularly relates to a thin film forming apparatus and a thin film forming method and to a method for producing a thin film semiconductor device capable of producing a high quality thin film and capable of producing a thin film semiconductor device able to be applied to a large-sized display device.
Note that, in the present invention, xe2x80x9csingle crystalline semiconductorxe2x80x9d is a concept including not only a single crystalline silicon, but also a single crystalline compound semiconductor, for example single As) and a single crystalline silicon-germanium (Sixe2x80x94Ge). Further, in the present invention, xe2x80x9csingle crystalxe2x80x9d is a concept including this even for a single crystal containing sub grain boundaries and dislocation.
In a thin film transistor (hereinafter referred to as a TFT) drive type liquid crystal display device, an amorphous silicon TFT has been used, but a polycrystalline silicon TFT has an electron field effect mobility of a high 100 or so in comparison with an amorphous silicon TFT and can be given higher performance, so an integral drive circuit type TFT has mainly been employed.
Conventionally, the technique of forming an amorphous silicon layer by plasma CVD or the like and crystallizing the polycrystalline silicon layer and improving the crystallinity by activation annealing by irradiation by a pulse-like excimer laser beam has been studied and developed.
However, the process of production of the semiconductor as described above has the following problems. Namely, in a method of producing a thin film transistor having a high mobility as a polycrystalline silicon film by melting an amorphous silicon film by irradiation of a laser such as an excimer laser or an argon laser to the amorphous silicon film and recrystallizing the same, since a laser such as an excimer laser or argon laser is used, there is the problem in that it is difficult to form a thin film in a large area and therefore the desired yield and quality can hardly ever be obtained.
Note that the technique of improving the excimer laser device so as to stabilize the excimer laser output and therefore enable formation of a thin film over a large area can be considered, but there was the problem that improvement of an excimer laser device is high in cost. In this way, in the prior art, there was a problem in improvement of the performance and quality and reduction of costs along with enlargement of the size of the substrate.
In order to solve the problems, recently, catalytic CVD enabling fabrication of a polycrystalline silicon film and a silicon nitride film on an insulating substrate such as a glass substrate at a low temperature has been developed and practical application studied.
Even by the technique using catalytic CVD, however, in the same way as with plasma CVD, there was the problem that a transition layer of the initial stage amorphous silicon (5 to 10 nm) was apt to be formed according to the substrate or film forming conditions if forming a polycrystalline silicon film on a glass substrate. In the case of a bottom gate type TFT, there was the problem that the desired electron mobility could hardly ever be obtained. A bottom gate type TFT is generally easily produced in terms of yield and productivity, so development of a technique for producing a high quality bottom gate type TFT has been demanded.
Further, there was the problem that when employing catalytic CVD, if the total film formation rate is small, the temperature of the substrate would rise or unevenness would occurred in the temperature of the substrate due to the radiant heat from a thermal catalyst and that variations would occur in the film thickness and the film quality.
The present invention was made in consideration with such a circumstance and has as its first object to provide a thin film forming apparatus and a thin film forming method for forming a high quality thin film on a substrate.
A second object of the present invention is to provide a thin film forming apparatus and a thin film forming method and a method for producing a thin film semiconductor device for forming a thin film having a high quality and able to be applied to also a large sized display device.
A third object of the present invention is to provide a thin film forming apparatus and a thin film forming method and a method for producing a thin film semiconductor device capable of forming a high quality thin film at a high speed.
A fourth object of the present invention is to provide a thin film forming apparatus and a thin film forming method and a method for producing a thin film semiconductor device making it possible to form a high quality thin film and produce a thin film semiconductor device and capable of preventing deterioration of a thermal catalyst.
The thin film forming apparatus of the present invention is a thin film forming apparatus comprising a vacuum chamber, a substrate, a thermal catalyst, and a heating means for heating the thermal catalyst, wherein a gas introduction system for introducing a gas is connected to the vacuum chamber and wherein the gas is fed from the gas introduction system into the vacuum chamber to form a thin film on a surface of the substrate by utilizing a thermal decomposition reaction and a catalytic reaction by the thermal catalyst, the gas introduction system introduces a carrier gas containing hydrogen and a material gas for forming a thin film on the substrate, and the carrier gas is fed into the vacuum chamber during at least the formation of the thin film.
In this way, when a thin film is formed on the substrate, the carrier gas containing hydrogen is constantly fed, so activated hydrogen H* generated in the carrier gas cleans the substrate surface and a high quality thin film can be formed on the substrate. Further, carrier gas containing hydrogen is constantly introduced during the film formation of the substrate, therefore the thermal catalyst is protected from influence of another gas, so it becomes possible to prevent the deterioration of the thermal catalyst.
Alternatively, the thin film forming apparatus of the present invention is a thin film forming apparatus comprising a vacuum chamber, a substrate, a thermal catalyst, and a heating means for heating the thermal catalyst, wherein a gas introduction system for introducing a gas is connected to the vacuum chamber and wherein the gas is fed from the gas introduction system into the vacuum chamber to form a thin film on a surface of the substrate by utilizing a thermal decomposition reaction and a catalytic reaction by the thermal catalyst, the gas introduction system introduces a carrier gas containing hydrogen and a material gas for forming the thin film on the substrate, and the apparatus comprises a means for raising a concentration of the material gas in the vacuum chamber in the middle of the formation of the thin film on the substrate.
The means for raising the concentration of the material gas is provided with a carrier gas controlling means for reducing or stopping the feed of for example the carrier gas.
In this way, when forming a thin film on the substrate, since a carrier gas containing hydrogen is used, the activated hydrogen H* generated in the carrier gas cleans the substrate surface, and a high quality thin film can be formed on the substrate. Further, since provision is made of a means for reducing or stopping the introduction of for example the carrier gas after an elapse of a predetermined time after the start of the film formation when forming various films, it is possible to form a thin film on the substrate at a high speed by raising a ratio of the material gas in the vacuum chamber and it becomes possible to improve workability.
At least a first material gas for forming a first thin film on the substrate and a second material gas for forming a second thin film on the substrate are fed from the gas introduction system. The first material gas and the second material gas are controlled by a material gas controlling means so that the second material gas is introduced after an elapse of a predetermined time after the first material gas is discharged from the vacuum chamber.
In the thin film forming apparatus of the present invention, since carrier gas containing hydrogen is constantly fed to the vacuum chamber, if the introduction of the material gas is controlled so that the second material gas is introduced after an elapse of a predetermined time after the first material gas is discharged as described above, the vacuum chamber will be filled with only the carrier gas containing hydrogen between the discharge of the first material gas and the introduction of the second material gas. Accordingly, it becomes possible to apply the cleaning to the substrate surface by the activated hydrogen H* after forming the first thin film. According to the present configuration, it becomes possible to clean the substrate surface by the activated hydrogen H* at every film formation, so it becomes possible to obtain a high quality thin film layer.
Further, it is also possible to control the introduction of the material gas by the material gas controlling means so that the second material gas is introduced at substantially the same time as the discharge of the first material gas from the vacuum chamber. In this way, by continuously introducing the material gas, the thin film layer can be obtained in a shorter time and thus it becomes possible to achieve an improvement of the work efficiency.
Further, it is also possible to control the introduction of the material gas by the material gas controlling means so that the second material gas is introduced into the vacuum chamber in a state where the first material gas remains in the vacuum chamber when the first material gas is discharged from the vacuum chamber.
In this way, by gradually reducing the amount of introduction of the first material gas and gradually increasing the amount of introduction of the second material gas, the first material gas and the second material gas will be mixed in the vacuum chamber while changing the occupation rate for a predetermined time. In this way, it becomes possible to form so-called inclined interface films comprised of a first thin film and a second thin film not clearly delineated in border. By stacking thin films by inclined interface, it is possible to reduce stress between films and it becomes possible to produce a semiconductor device having a higher quality semiconductor-insulator interface structure.
The gas introduction system is provided with a gas spraying portion located in the vacuum chamber. If changing the distance of this gas spraying portion from the thermal catalyst by a position adjusting means, it becomes possible to position the gas spraying portion at a position where the best catalytic reaction is obtained in accordance with a broadness of the vacuum chamber or the types of the gas and the thermal catalyst or the shape and the size of the thermal catalyst.
Further, if enabling the distance between the thermal catalyst and the substrate to be adjusted in the vacuum chamber by holding the thermal catalyst by a moveable thermal catalyst holding means, it becomes possible to position the thermal catalyst at a position where the best catalytic reaction is obtained in accordance with the broadness of the vacuum chamber or the types of the gas and the thermal catalyst or the shape and the size of the thermal catalyst and the substrate. Further, it is also possible to dispose a shutter between the thermal catalyst and a substrate holder (substrate) according to need. By this, contamination from the thermal catalyst at the time of a temperature rise or a temperature drop of the thermal catalyst can be prevented and further inadequate film formation by the materials at that time in an insufficient thermal decomposition reaction and thermal catalytic reaction can be prevented.
Further, it is also possible to employ a configuration capable of adjusting the distance between the substrate and the thermal catalyst in the vacuum chamber by placing the substrate on the moveable substrate holder. Further, by rotating the substrate holder or placing it at any angle with respect to the thermal catalyst, it becomes possible to improve the film thickness and film quality uniformity in the substrate. When employing such a configuration, it becomes possible to position the substrate at a position where the best catalytic reaction is obtained in accordance with the broadness of the vacuum chamber or the types of the gas and the thermal catalyst or the shape and the size of the thermal catalyst.
Furthermore, by laying a rail in the vacuum chamber, attaching a means moveable on the rail to the substrate holder, and making the substrate holder moveable on the rail, for example, as described in the embodiment, it becomes possible to move the substrate holder along a long thermal catalyst arranged in the vacuum chamber, it becomes possible to uniformly apply the film formation to the substrate, and it becomes possible to reduce cost by the improvement of the productivity.
A plurality of thermal catalysts can be arranged in the vacuum chamber. It is possible to form these thermal catalysts by the same material or by materials different from each other. By freely selecting and combining the materials of the thermal catalysts in this way, it becomes possible to obtain the best catalytic reaction.
Further, it is also possible to arrange a plurality of thermal catalysts in the vacuum chamber and form these thermal catalysts in the same shape or different shapes. By freely selecting and combining the shapes of the thermal catalysts in this way, it becomes possible to obtain the best catalytic reaction.
Further, it is also possible to arrange a plurality of thermal catalysts in the vacuum chamber and connect these thermal catalysts to power supplies for supplying the same current or power supplies for supplying different currents. By this, for example, even when a plurality of thermal catalysts are formed by materials different from each other, temperature adjustment of the thermal catalysts as resistance heat generators becomes possible by adjustment of the voltage and/or the current of the power supply, so a good catalytic reaction can be obtained. Further, even in a case where thermal catalysts made of the same materials are used, it becomes possible to adjust the heating temperature of the thermal catalysts in accordance with positions of the thermal catalysts in the vacuum chamber or the sizes of the thermal catalysts per se. Note that, as the power supply, use is made of a DC power supply or an AC power supply.
As the thermal catalyst, it is preferred to select one from the group consisting of tungsten, tungsten containing thoria, platinum, molybdenum, palladium, tantalum, metal deposited ceramics, silicon, alumina, silicon carbide, refractory metals (tungsten, tantalum, tungsten containing thoria, molybdenum, titanium, etc.) coated with silicon carbide or ceramics or conductive nitride films, silicon nitride or oxide, conductive metal nitrides (tungsten nitride, titanium nitride, molybdenum nitride, tantalum nitride, etc.), boronitride (BN), and silicide.
As the substrate, it is preferred to select from among semiconductor or insulating materials including silicon, germanium, silicon germanium, silicon carbide, gallium arsenic, gallium aluminum arsenic, gallium phosphorus, indium phosphorus, zinc selenide, cadmium sulfide, quartz glass, borosilicate glass, aluminosilicate glass, and heat resistant resins.
Note that preferably the thin film to be formed on the substrate contains a gate insulating film, and the gate insulating film is selected from among a silicon oxide film, silicon nitride film, silicon oxynitride film, aluminum nitride film, aluminum oxide film, tantalum oxide film, or composite films of the same.
Further, it is also possible to constitute the thin film forming apparatus for forming a thin film by a single chamber or a multi-chamber. By constituting it by a single chamber, it becomes possible to continuously form a plurality of thin films in the same chamber, for example, inclined interface films can be formed by gradually reducing or increasing two types of the material gases in a single chamber, and it becomes possible to form high quality thin films having a reduced stress between films.
Further, when forming a thin film in a multi-chamber, predetermined thin film formation is carried out in each of the chambers, therefore it becomes possible to obtain a high work efficiency.
According to the thin film forming apparatus, it is possible to form a semiconductor thin film such as polycrystalline silicon, single crystalline silicon, amorphous silicon, microcrystalline silicon, silicon germanium, silicon carbide, compound semiconductor (gallium arsenic, gallium phosphorus, gallium nitride, etc.), diamond, and diamond-like carbon (DLC), an insulator thin film such as silicon oxide, silicon oxide containing impurities (phosphosilicate glass (PSG), borosilicate glass (BSG), borophosphosilicate glass (BPSG), etc.), silicon nitride, silicon oxynitride, molybdenum oxide, titanium oxide, tantalum oxide, and aluminum oxide, an oxidative conductive thin film such as ruthenium oxide, indium oxide, indium tin oxide (ITO), iridium oxide, and palladium oxide, a metal thin film made by a refractory metal and conductive metal nitride thin film (tungsten, titanium, tantalum, molybdenum, tungsten nitride, titanium nitride, tantalum nitride, molybdenum nitride, etc.), silicide, copper, aluminum, aluminum-silicon or aluminum-silicon-copper, a high dielectric constant thin film such as BST, and a ferroelectric thin film such as PZT, PLZT, SBT, and BIT. The formation of various metal thin films is possible in this way.
Further, according to the thin film forming apparatus, it is possible to use the same as an apparatus for producing a silicon semiconductor device, a silicon semiconductor integrated circuit device, a silicon-germanium semiconductor device, a silicon-germanium semiconductor integrated circuit device, a compound semiconductor device, a compound semiconductor integrated circuit device, a silicon carbide semiconductor device, a silicon carbide semiconductor integrated circuit device, a diamond semiconductor device, a diamond semiconductor integrated circuit device, a liquid crystal display device, an electroluminescence display device, a plasma display panel (PDP) device, a light emission polymer display device, a light emission diode display device, a CCD area/linear sensor device, a MOS sensor device, a high dielectric/ferroelectric memory semiconductor device, a high dielectric/ferroelectric memory semiconductor integrated circuit device, a solar battery, and so on.
The thin film forming method of the present invention is a method for forming a thin film on a substrate in a vacuum chamber by catalytic CVD or high density plasma CVD or high density catalytic CVD, characterized in that it comprises a cleaning step of feeding a carrier gas containing hydrogen to the vacuum chamber and cleaning the top of the substrate by activated hydrogen H* generated in the fed carrier gas and a thin film forming step of forming the thin film on the substrate by feeding a material gas to the vacuum chamber, thin films being stacked on the substrate by repeating the cleaning step and the thin film forming step or repeating the thin film forming step after the cleaning step.
In this way, when forming a thin film on the substrate, carrier gas containing hydrogen is constantly fed, so the activated hydrogen H* generated in the carrier gas cleans the substrate surface and a high quality thin film can be formed on the substrate. Further, by feeding hydrogen gas as the carrier gas, heating the thermal catalyst to a state enabling the catalytic action, and continuously forming at least a silicon film and a gate insulating film, a low stress and a low contamination can be achieved in a gate channel portion. Further, since carrier gas containing hydrogen is constantly introduced during the film formation of the substrate, the thermal catalyst will be protected from the influence of the other gas and it becomes possible to prevent the deterioration of the thermal catalyst.
Alternatively, the thin film forming method of the present invention is a method for forming a thin film on a substrate in a vacuum chamber by catalytic CVD or high density plasma CVD or high density catalytic CVD, characterized in that it comprises a cleaning step of feeding a carrier gas containing hydrogen to the vacuum chamber and cleaning the top of the substrate by activated hydrogen H* generated in the fed carrier gas and a thin film forming step of forming a thin film on the substrate by feeding a material gas to the vacuum chamber, a silicon film being formed in at least a thin film semiconductor device forming region of the substrate and at least a gate insulating film being formed continuing from the silicon film by repeating the cleaning step and the thin film forming step or repeating the thin film forming step after the cleaning step.
As described above, when forming a thin film layer for a so-called top gate type TFT having a gate insulating film on a silicon film on a substrate, since carrier gas containing hydrogen is constantly fed, the activated hydrogen H* generated in the carrier gas cleans the substrate surface and a high quality thin film can be formed on the substrate. Further, by feeding hydrogen gas as the carrier gas, heating the thermal catalyst to a state enabling a catalytic action, and continuously forming at least a silicon film and a gate insulating film, a low stress and a low contamination can be achieved in the gate channel portion. Further, since carrier gas containing hydrogen is constantly introduced during the film formation of the substrate, the thermal catalyst will be protected from the influence of another gas and it becomes possible to prevent deterioration of the thermal catalyst.
Alternatively, the thin film forming method of the present invention is a method for forming a thin film on a substrate in a vacuum chamber by catalytic CVD or high density plasma CVD or high density catalytic CVD, characterized in that it comprises a cleaning step of feeding a carrier gas containing hydrogen to the vacuum chamber and cleaning the top of the substrate by activated hydrogen H* generated in the fed carrier gas and a thin film forming step of forming the thin film on the substrate by feeding a material gas to the vacuum chamber, at least a gate insulating film being formed in at least the thin film semiconductor device forming region of the substrate with a gate electrode formed in advance therein, and at least a silicon film being formed continuing from the related gate insulating film by repeating the cleaning step and the thin film forming step or repeating the thin film forming step after the cleaning step.
As described above, when forming a thin film layer for a so-called bottom gate type TFT having a gate insulating film and a silicon film on the substrate with the gate electrode formed in advance therein on the substrate, since carrier gas containing hydrogen is constantly fed, the activated hydrogen H* generated in the carrier gas cleans the substrate surface, and a high quality thin film can be formed on the substrate. Further, by feeding hydrogen gas as the carrier gas, heating the thermal catalyst to a state enabling a catalytic action, and continuously forming at least a silicon film and a gate insulating film, a low stress and a low contamination can be achieved in the gate channel portion. Further, since the carrier gas containing hydrogen is constantly introduced during the film formation of the substrate, the thermal catalyst will be protected from the influence of another gas and it becomes possible to prevent the deterioration of the thermal catalyst.
In this way, according to the present method, it becomes possible to form a thin film layer for a bottom gate type TFT excellent in yield and productivity with a high quality.
Alternatively, the thin film forming method of the present invention is a method for forming a thin film on a substrate in a vacuum chamber by catalytic CVD or high density plasma CVD or high density catalytic CVD, characterized in that it comprises a cleaning step of feeding a carrier gas containing hydrogen to the vacuum chamber and cleaning the top of the substrate by activated hydrogen H* generated in the fed carrier gas and a thin film forming step of forming the thin film on the substrate by feeding a material gas to the vacuum chamber, at least a first gate insulating film being formed in at least the thin film semiconductor device forming region of the substrate with a first gate electrode formed in advance therein, and at least a silicon film being formed continuing from the first gate insulating film, thereby to form a first thin film layer, and at least a second gate insulating film for a second gate electrode being formed continuing from the first thin film layer by repeating the cleaning step and the thin film forming step or repeating the thin film forming step after the cleaning step.
In this way, when forming a thin film for a so-called dual gate type semiconductor device wherein the first gate insulating film and the silicon film are continuously formed on the substrate with the first gate electrode formed in advance therein and the second gate insulating film is formed continuing from this silicon film, since the carrier gas containing hydrogen is constantly fed, the activated hydrogen H* generated in the carrier gas cleans the substrate surface, and a high quality thin film can be formed on the substrate. Further, by feeding hydrogen gas as the carrier gas, heating the thermal catalyst to a state enabling a catalytic action, and continuously forming at least the silicon film and the gate insulating film, a low stress and a low contamination can be achieved in the gate channel portion. Further, since the carrier gas containing hydrogen is constantly introduced during the film formation of the substrate, the thermal catalyst will be protected from the influence of another gas and it becomes possible to prevent the deterioration of the thermal catalyst.
In this way, according to the method of the present invention, it becomes possible to form a thin film layer for a dual gate type TFT excellent in electrical control with a high quality and at a high speed.
Further, in the thin film forming step, by feeding the first material gas to the vacuum chamber and feeding the second material gas to the vacuum chamber in the state where the first material gas remains in the vacuum chamber, the thin film formed by the second material gas is joined by inclined interface onto the thin film formed by the second material gas and stacked on the substrate, whereby the stress between adjoining films can be reduced.
In this way, by feeding the second material gas to the vacuum chamber in the state where the first material gas remains in the vacuum chamber, the first material gas and the second material gas will be mixed in the chamber 1 while changing in occupation rate over a predetermined time. In this way, so-called inclined interface films wherein the first thin film and the second thin film are not clearly delineated in border can be obtained. By stacking the thin films by an inclined interface, it is possible to reduce the stress between films, and it becomes possible to produce a semiconductor device with a higher quality.
Note that it is preferred if a step is formed in at least the semiconductor device forming region of the substrate and a single crystalline semiconductor film is grapho-epitaxially grown on the substrate containing the step. Namely, since a step is provided in the substrate and a single crystalline semiconductor film is grapho-epitaxially grown on the substrate containing the step, a single crystalline semiconductor film having a high electron mobility and excellent in operability can be obtained.
Further, it is preferred if a substance layer having a good lattice alignment with the single crystalline semiconductor is formed in at least the semiconductor device forming region of the substrate and the single crystalline semiconductor film is hetero-epitaxially grown on the substrate containing the substance layer. Namely, since a substance layer having a good lattice alignment with a single crystalline semiconductor is formed on the substrate and the single crystalline semiconductor film is hetero-epitaxially grown on the substrate containing this substance layer, a single crystalline semiconductor film having a high electron mobility and excellent in operability can be obtained.
Note that as the substance layer having a good lattice alignment with a single crystalline semiconductor, preferably use is made of a substance selected from a group consisting of sapphire, a spinel structure, and calcium fluoride.
Further, the thin film may be formed in a single chamber or formed in a multi-chamber. By forming the thin film in a single chamber, it becomes possible to continuously form a plurality of thin films in the same chamber. Further, by gradually reducing or increasing two types of material gases in the single chamber, inclined interface films can be formed, and it becomes possible to form high quality thin films having a reduced stress between films. Further, when forming a thin film in a multi-chamber, since a predetermined thin film formation is carried out in each chamber, it becomes possible to obtain a high work efficiency.
Note that catalytic CVD is a method for activating and ionizing at least one part of a material by a catalytic reaction or a thermal decomposition reaction for the thermal catalyst heated to less than the melting point and depositing these deposition seeds on a heated substrate.
Further, it is also possible to employ a configuration capable of adjusting the distance between the substrate and the thermal catalyst in the vacuum chamber by placing the substrate on a moveable substrate holder. When employing such a configuration, it becomes possible to position the substrate at a position where the best catalytic reaction is obtained in accordance with the broadness of the vacuum chamber or the types of the gas and the thermal catalyst or the shape and the size of the thermal catalyst.
It is preferred if the thermal catalyst is selected from at least one type of material selected from a group consisting of tungsten, tungsten containing thoria, platinum, molybdenum, palladium, tantalum, metal deposited ceramics, silicon, alumina, silicon carbide, refractory metal (tungsten, tantalum, tungsten containing thoria, molybdenum, titanium, etc.) coated with silicon carbide or ceramics or conductive nitride films, silicon nitride or oxide, conductive metal nitride (tungsten nitride, titanium nitride, molybdenum nitride, tantalum nitride, etc.), boronitride (BN), and silicide. Further, if the thermal catalyst is held by a moveable thermal catalyst holding means and thereby it is made possible to adjust the distance from the substrate, it becomes possible to position the thermal catalyst at a position where the best catalytic reaction is obtained in accordance with the broadness of the vacuum chamber or the types of the gas and the thermal catalyst or the shape and the size of the thermal catalyst.
It is possible to arrange a plurality of thermal catalysts in the vacuum chamber. It is possible to form these thermal catalysts by the same material or different materials from each other. By freely selecting and combining the materials of the thermal catalysts in this way, it becomes possible to obtain the best catalytic reaction.
Further, it is possible to arrange a plurality of thermal catalysts in the vacuum chamber and form these thermal catalysts in the same shape or different shapes. By freely selecting and combining the shapes of the thermal catalysts in this way, it becomes possible to obtain the best catalytic reaction.
Alternatively, it is also possible to employ a configuration arranging a plurality of thermal catalysts in the vacuum chamber and connecting these thermal catalysts to the same current-voltage supply or different current-voltage supplies. By this, even if for example a plurality of thermal catalysts are formed by materials different from each other, temperature adjustment of the thermal catalysts as the resistance heat generators becomes possible by voltage-current adjustment of the power supply, and thus a good catalytic reaction can be obtained. Further, even in the case where thermal catalysts made of the same material are used, it becomes possible to adjust the heating temperature of the thermal catalysts in accordance with the positions of the thermal catalysts in the vacuum chamber or the sizes of the thermal catalysts per se. Note that, as the power supply, use is made of a DC power supply or an AC power supply or a power supply wherein the AC is superposed on the DC.
More specifically, one or more thin films of a semiconductor thin film such as polycrystalline silicon, single crystalline silicon, amorphous silicon, microcrystalline silicon, silicon germanium, silicon carbide, compound semiconductor (gallium arsenic, gallium phosphorus, gallium nitride, etc.), diamond, and diamond-like carbon (DLC), an insulator thin film such as silicon oxide, silicon oxide containing impurities (phosphosilicate glass (PSG), borosilicate glass (BSG), borophosphosilicate glass (BPSG), etc.), silicon nitride, silicon oxynitride, molybdenum oxide, titanium oxide, tantalum oxide, and aluminum oxide, an oxidative conductive thin film such as ruthenium oxide, indium oxide, indium tin oxide (ITO), iridium oxide, and palladium oxide, a metal thin film made by a refractory metal and conductive metal nitride thin film (tungsten, titanium, tantalum, molybdenum, tungsten nitride, titanium nitride, tantalum nitride, molybdenum nitride, etc.), silicide, copper, aluminum, aluminum-silicon or aluminum-silicon-copper, a high dielectric rate thin film such as BST, and the ferroelectric thin film such as PZT, PLZT, SBT, and BIT is formed.
Then, a silicon nitride film is formed by a gas containing hydrogen as the carrier gas and containing a silane-based gas such as monosilane, disilane, or trisilane as the material gas and ammonia, a silicon oxide film is formed by a gas containing hydrogen as the carrier gas and containing a silane-based gas such as monosilane, disilane, or trisilane as the material gas and an inert gas-diluted oxygen (for example argon- or helium-diluted oxygen) or an inert gas (for example argon- or helium-diluted ozone), and a polycrystalline silicon film is formed by a gas containing hydrogen as the carrier gas and containing at least one of monosilane, disilane, and trisilane as the material gas.
Note that, in the polycrystalline silicon film and the single crystalline silicon film, in order to control the carrier impurity concentration, phosphine, arsine and stibine are mixed into the silane-based gas containing monosilane, disilane, and trisilane in an appropriate amount to achieve an N-type, and diborane is mixed into the silane-based gas containing monosilane, disilane, and trisilane to achieve a P-type.
As the substrate, it is preferred to select it from among semiconductor or insulating materials including silicon, germanium, silicon germanium, silicon carbide, gallium arsenic, gallium aluminum arsenic, gallium phosphorus, indium phosphorus, zinc selenide, cadmium sulfide, quartz glass, borosilicate glass, aluminosilicate glass, and heat resistant resins.
Note that, preferably the thin film to be formed on the substrate includes a gate insulating film, and the gate insulating film is selected from among a silicon oxide film, silicon nitride film, silicon oxynitride film, aluminum nitride film, aluminum oxide film, tantalum oxide film, or composite films of the same.
The method for producing a thin film forming semiconductor device of the present invention is a method for producing a thin film semiconductor device containing a thin film layer by forming a thin film layer on a substrate in a vacuum chamber by catalytic CVD or high density plasma CVD or high density catalytic CVD, characterized in that it comprises a cleaning step of constantly feeding a carrier gas containing hydrogen to the vacuum chamber and cleaning the top of the substrate by activated hydrogen H* generated in the fed carrier gas, a thin film forming step of forming the thin film on the substrate by feeding a material gas to the vacuum chamber, and a step of stacking thin films on the substrate to form a thin film layer by repeating the cleaning step and the thin film forming step or repeating the thin film forming step after the cleaning step and of applying predetermined processing to the thin film layer to fabricate a semiconductor element.
The method for producing a top gate type TFT of the present invention is a method for producing a thin film semiconductor device containing a thin film layer by forming a thin film layer on a substrate in a vacuum chamber by catalytic CVD or high density plasma CVD or high density catalytic CVD, characterized in that it comprises a cleaning step of constantly feeding a carrier gas containing hydrogen to the vacuum chamber and cleaning the top of the substrate by activated hydrogen H* generated in the fed carrier gas, a thin film forming step of forming a thin film on the substrate by feeding a material gas to the vacuum chamber, and a step of forming a silicon film in at least the thin film semiconductor device forming region of the substrate and forming at least a gate insulating film continuing from the silicon film by repeating the cleaning step and the thin film forming step or repeating the thin film forming step after the cleaning step to thereby form the thin film layer and applying predetermined processing to the thin film layer to fabricate a top gate type TFT.
The method for producing a bottom gate type TFT of the present invention is a method for producing a thin film semiconductor device containing a thin film layer by forming a thin film layer on a substrate in a vacuum chamber by catalytic CVD or high density plasma CVD or high density catalytic CVD, characterized in that it comprises a cleaning step of constantly feeding a carrier gas containing hydrogen to the vacuum chamber and cleaning the top of the substrate by activated hydrogen H* generated in the fed carrier gas, a thin film forming step of forming a thin film on the substrate by feeding a material gas to the vacuum chamber, and a step of forming at least a gate insulating film in at least the thin film semiconductor device forming region of the substrate with a gate electrode formed in advance therein and forming at least a silicon film continuing from the gate insulating film by repeating the cleaning step and the thin film forming step or repeating the thin film forming step after the cleaning step to thereby form a thin film layer and applying predetermined processing to the thin film layer to fabricate a bottom gate type TFT.
The method for producing a dual gate type TFT of the present invention is a method for producing a thin film semiconductor device containing a thin film layer by forming a thin film layer on a substrate in a vacuum chamber by catalytic CVD or high density CVD or high density catalytic CVD, characterized in that it comprises a cleaning step of constantly feeding a carrier gas containing hydrogen to the vacuum chamber and cleaning the top of the substrate by activated hydrogen H* generated in the fed carrier gas, a thin film forming step of forming a thin film on the substrate by feeding a material gas to the vacuum chamber, and a step of repeating the cleaning step and the thin film forming step or repeating the thin film forming step after the cleaning step to form at least a first gate insulating film in at least the thin film semiconductor device forming region of the substrate with a first gate electrode formed in advance therein, form a first thin film layer by forming at least a silicon film continuing from the first gate insulating film, and form a second thin film layer by forming a second gate insulating film for at least a second gate electrode continuing from the first thin film layer and applying predetermined processing to the first thin film layer and second thin film layer to thereby fabricate a dual gate type TFT.
In this way, in the methods, since the carrier gas containing hydrogen is constantly fed, the activated hydrogen H* generated in the carrier gas cleans the substrate surface, so a high quality thin film can be formed on the substrate. Further, by feeding hydrogen gas as the carrier gas, heating the thermal catalyst to a state enabling a catalytic action, and continuously forming at least the silicon film and the gate insulating film, a low stress and a low contamination can be achieved in the gate channel portion.
Then, since semiconductor elements are fabricated by applying predetermined processing to the high quality thin film layer obtained by the methods of the inventions, it becomes possible to obtain various high quality thin film semiconductor devices.
Further, according to the methods of the present invention, since carrier gas containing hydrogen is constantly introduced during the formation of the substrate, the thermal catalyst will be protected from the influence of another gas, and it becomes possible to prevent the deterioration of the thermal catalyst.
Further, by employing a configuration wherein a step is formed in at least the semiconductor device forming region of the substrate and a single crystalline semiconductor film is grapho-epitaxially grown on the substrate containing the step or employing a configuration wherein a substance layer having a good lattice alignment with the single crystalline semiconductor is formed in at least the semiconductor device forming region of the substrate and the single crystalline semiconductor film is hetero-epitaxially grown on the substrate containing the substance layer, it is possible to obtain a single crystalline semiconductor film having a high electron mobility and excellent in operability.
Further, it is preferred to apply the thin film layer to a channel region, a source region, or a drain region of an insulating gate type field effect transistor and control the types of the impurities injected into these regions and/or concentrations.
Further, according to the method for producing the thin film semiconductor device, it is possible to produce a silicon semiconductor device, silicon semiconductor integrated circuit device, silicon-germanium semiconductor device, silicon-germanium semiconductor integrated circuit device, compound semiconductor device, compound semiconductor integrated circuit device, silicon carbide semiconductor device, silicon carbide semiconductor integrated circuit device, diamond semiconductor device, diamond semiconductor integrated circuit device, liquid crystal display device, electroluminescence display device, plasma display panel (PDP) device, light emission polymer display device, light emission diode display device, CCD area/linear sensor device, MOS sensor device, high dielectric/ferroelectric memory semiconductor device, high dielectric/ferroelectric memory semiconductor integrated circuit device, solar battery, and so on.
Further, the thin film forming method of the present invention is a method for forming a thin film on a substrate in a vacuum chamber by catalytic CVD or high density CVD or high density catalytic CVD, characterized in that it comprises a cleaning step of feeding a carrier gas containing hydrogen to the vacuum chamber and cleaning the top of the substrate by the activated hydrogen H* generated in the carrier gas, a thin film forming step of forming a thin film on the substrate by feeding a material gas to the vacuum chamber, and a carrier gas stopping step of reducing or stopping the feed of the carrier gas, thin films being stacked on the substrate by repeating the cleaning step and the thin film forming step and the carrier gas stopping step or repeating the thin film forming step and the carrier gas stopping step after the cleaning step.
In this way, by the carrier gas stopping step of reducing or stopping the feed of the carrier gas, when forming various films, after the elapse of a predetermined time after the start of the film formation, the introduction of the carrier gas is reduced or stopped, therefore the ratio of the material gas becomes high in the vacuum chamber, the formation of the thin film onto the substrate is carried out at a high speed, and it becomes possible to improve the workability. Further, when forming a thin film on a substrate, since a carrier gas containing hydrogen is fed, the activated hydrogen H* generated in the carrier gas cleans the substrate surface, thus a high quality thin film can be formed on the substrate. Further, by feeding hydrogen gas as the carrier gas, heating the thermal catalyst to a state enabling a catalytic action, and continuously forming at least the silicon film and the gate insulating film, a low stress and low contamination can be achieved in the gate channel portion.
Alternatively, the thin film forming method of the present invention is a method for forming a thin film on a substrate in a vacuum chamber by catalytic CVD or high density CVD or high density catalytic CVD, characterized in that it comprises a cleaning step of feeding a carrier gas containing hydrogen to the vacuum chamber and cleaning the top of the substrate by the activated hydrogen H* generated in the carrier gas, a thin film forming step of forming a thin film on the substrate by feeding a material gas to the vacuum chamber, and a carrier gas stopping step of reducing or stopping the feed of the carrier gas, a silicon film being formed in at least the thin film semiconductor device forming region of the substrate and at least a gate insulating film being formed continuing from the silicon film by repeating the cleaning step and the thin film forming step and the carrier gas stopping step or repeating the thin film forming step and the carrier gas stopping step after the cleaning step.
As described above, when forming a thin film layer for a so-called top gate type TFT having a gate insulating film on a silicon film on a substrate, by the carrier gas stopping step of reducing or stopping the feed of the carrier gas, when forming various films, after the elapse of a predetermined time after the start of the film formation, the introduction of the carrier gas is reduced or stopped, therefore the ratio of the material gas becomes high in the vacuum chamber, the formation of the thin film onto the substrate is carried out at a high speed, and it becomes possible to improve the workability. Further, when forming a thin film on a substrate, since a carrier gas containing hydrogen is fed, the activated hydrogen H* generated in the carrier gas cleans the substrate surface, and thus a high quality thin film can be formed on the substrate. Further, by feeding hydrogen gas as the carrier gas, heating the thermal catalyst to a state enabling a catalytic action, and continuously forming at least the silicon film and the gate insulating film, a low stress and low contamination can be achieved in the gate channel portion.
Alternatively, the thin film forming method of the present invention is a method for forming the thin film on the substrate in the vacuum chamber by catalytic CVD or high density CVD or high density catalytic CVD, characterized in that it comprises a cleaning step of feeding a carrier gas containing hydrogen to the vacuum chamber and cleaning the top of the substrate by the activated hydrogen H* generated in the carrier gas, a thin film forming step of forming a thin film on the substrate by feeding a material gas to the vacuum chamber, and a carrier gas stopping step of reducing or stopping the feed of the carrier gas, at least a gate insulating film being formed in at least the thin film semiconductor device forming region of the substrate with thegate electrode formed in advance therein and at a least silicon film being formed continuing from the gate insulating film by repeating the cleaning step and the thin film forming step and the carrier gas stopping step or repeating the thin film forming step and the carrier gas stopping step after the cleaning step.
As described above, when forming a thin film layer for a so-called bottom gate type TFT having a gate insulating film and a silicon film on the substrate with the gate electrode formed in advance therein on the substrate, by the carrier gas stopping step of reducing or stopping the feed of the carrier gas, when forming various films, after the elapse of a predetermined time after the start of the film formation, the introduction of the carrier gas is reduced or stopped, therefore the ratio of the material gas becomes high in the vacuum chamber, the formation of the thin film onto the substrate is carried out at a high speed, and it becomes possible to improve the workability. Further, when forming the thin film on the substrate, since the carrier gas containing hydrogen is fed, the activated hydrogen H* generated in the carrier gas cleans the substrate surface, and thus a high quality thin film can be formed on the substrate. Further, by feeding hydrogen gas as the carrier gas, heating the thermal catalyst to a state enabling a catalytic action, and continuously forming at least the silicon film and the gate insulating film, a low stress and low contamination can be achieved in the gate channel portion.
In this way, according to the method of the present invention, it becomes possible to form a thin film layer for a bottom gate type TFT excellent in yield and productivity with a high quality and at a high speed.
Alternatively, the thin film forming method of the present invention is a method for forming a thin film on a substrate in a vacuum chamber by catalytic CVD or high density CVD or high density catalytic CVD, characterized in that it comprises a cleaning step of feeding a carrier gas containing hydrogen to the vacuum chamber and cleaning the top of the substrate by the activated hydrogen H* generated in the carrier gas, a thin film forming step of forming a thin film on the substrate by feeding a material gas to the vacuum chamber, and a carrier gas stopping step of reducing or stopping the feed of the carrier gas, at least a first gate insulating film being formed in at least the thin film semiconductor device forming region of the substrate with a first gate electrode formed in advance therein and at a least silicon film being formed continuing from the first gate insulating film to form a first thin film layer and a second gate insulating film for at least a second gate electrode being formed continuing from the first thin film layer by repeating the cleaning step and the thin film forming step and the carrier gas stopping step or repeating the thin film forming step and the carrier gas stopping step after the cleaning step.
In this way, when forming a thin film for a so-called dual gate type semiconductor device wherein a first gate insulating film and a silicon film are continuously formed on a substrate with a first gate electrode formed in advance therein and the second gate insulating film is formed continuing from this silicon film on the substrate, by the carrier gas stopping step of reducing or stopping the feed of the carrier gas, when forming various films, after the elapse of a predetermined time after the start of the film formation, the introduction of the carrier gas is reduced or stopped, therefore the ratio of the material gas becomes high in the vacuum chamber, the formation of the thin film onto the substrate is carried out at a high speed, and it becomes possible to improve the workability. Further, when forming a thin film on a substrate, since a carrier gas containing hydrogen is fed, the activated hydrogen H* generated in the carrier gas cleans the substrate surface, thus a high quality thin film can be formed on the substrate. Further, by feeding hydrogen gas as the carrier gas, heating the thermal catalyst to a state enabling a catalytic action, and continuously forming at least the silicon film and the gate insulating film, a low stress and low contamination can be achieved in the gate channel portion.
In this way, according to the method of the present invention, it becomes possible to form a thin film layer for a dual gate type TFT excellent in electrical control with a high quality and at a high speed.
Further, in the thin film forming step, by feeding the first material gas to the vacuum chamber and feeding the second material gas to the vacuum chamber in the state where the first material gas remains in the vacuum chamber, the thin film formed by the second material gas is joined by inclined interface onto the thin film formed by the first material gas and stacked on the substrate, whereby the stress between adjoining films can be reduced.
In this way, by feeding the second material gas to the vacuum chamber in the state where the first material gas remains in the vacuum chamber, the first material gas and the second material gas will be mixed in the chamber 1 while changing in occupation rate over a predetermined time. In this way, so-called inclined interface films wherein the first thin film and the second thin film are not clearly delineated in border can be obtained. By stacking the thin films by an inclined interface, it is possible to reduce the stress between films, and it becomes possible to produce a semiconductor device with a higher quality.
Note that it is preferred if a step is formed in at least the semiconductor device forming region of the substrate and a single crystalline semiconductor film is grapho-epitaxially grown on the substrate containing the step. Namely, since a step is provided in the substrate and a single crystalline semiconductor film is grapho-epitaxially grown on the substrate containing the step, a single crystalline semiconductor film having a high electron mobility and excellent in operability can be obtained.
Further, it is preferred if a substance layer having a good lattice alignment with the single crystalline semiconductor is formed in at least the semiconductor device forming region of the substrate and the single crystalline semiconductor film is hetero-epitaxially grown on the substrate containing the substance layer. Namely, since a substance layer having a good lattice alignment with a single crystalline semiconductor is formed on the substrate and the single crystalline semiconductor film is hetero-epitaxially grown on the substrate containing this substance layer, a single crystalline semiconductor film having a high electron mobility and excellent in operability can be obtained.
Note that as the substance layer having a good lattice alignment with a single crystalline semiconductor, preferably use is made of a substance selected from a group consisting of sapphire, a spinel structure, and calcium fluoride.
Further, the thin film may be formed in a single chamber or formed in a multi-chamber. By forming the thin film in a single chamber, it becomes possible to continuously form a plurality of thin films in the same chamber. Further, by gradually reducing or increasing two types of material gases in the single chamber, inclined interface films can be formed, and it becomes possible to form high quality thin films having a reduced stress between films. Further, when forming a thin film in a multi-chamber, since a predetermined thin film formation is carried out in each chamber, it becomes possible to obtain a high work efficiency.
Note that catalytic CVD is a method for activating and ionizing at least one part of a material by a catalytic reaction or a thermal decomposition reaction for the thermal catalyst heated to less than the melting point and depositing these deposition seeds on a heated substrate.
Further, it is also possible to employ a configuration capable of adjusting the distance between the substrate and the thermal catalyst in the vacuum chamber by placing the substrate on a moveable substrate holder. When employing such a configuration, it becomes possible to position the substrate at a position where the best catalytic reaction is obtained in accordance with the broadness of the vacuum chamber or the types of the gas and the thermal catalyst or the shape and the size of the thermal catalyst.
It is preferred if the thermal catalyst is selected from at least one type of material selected from a group consisting of tungsten, tungsten containing thoria, platinum, molybdenum, palladium, tantalum, metal deposited ceramics, silicon, alumina, silicon carbide, refractory metal (tungsten, tantalum, tungsten containing thoria, molybdenum, titanium, etc.) coated with silicon carbide or ceramics or conductive nitride films, silicon nitride or oxide, conductive metal nitride (tungsten nitride, titanium nitride, molybdenum nitride, tantalum nitride, etc.), boronitride (BN), and silicide.
Further, if the thermal catalyst is held by a moveable thermal catalyst holding means and thereby it is made possible to adjust the distance from the substrate, it becomes possible to position the thermal catalyst at a position where the best catalytic reaction is obtained in accordance with the broadness of the vacuum chamber or the types of the gas and the thermal catalyst or the shape and the size of the thermal catalyst.
It is possible to arrange a plurality of thermal catalysts in the vacuum chamber. It is possible to form these thermal catalysts by the same material or different materials from each other. By freely selecting and combining the materials of the thermal catalysts in this way, it becomes possible to obtain the best catalytic reaction.
Further, it is possible to arrange a plurality of thermal catalysts in the vacuum chamber and form these thermal catalysts in the same shape or different shapes. By freely selecting and combining the shapes of the thermal catalysts in this way, it becomes possible to obtain the best catalytic reaction.
Alternatively, it is also possible to employ a configuration arranging a plurality of thermal catalysts in the vacuum chamber and connecting these thermal catalysts to the same current-voltage supply or different current-voltage supplies. By this, even if for example a plurality of thermal catalysts are formed by materials different from each other, temperature adjustment of the thermal catalysts as the resistance heat generators becomes possible by voltage-current adjustment of the power supply, and thus a good catalytic reaction can be obtained. Further, even in the case where thermal catalysts made of the same material are used, it becomes possible to adjust the heating temperature of the thermal catalysts in accordance with the positions of the thermal catalysts in the vacuum chamber or the sizes of the thermal catalysts per se. Note that, as the power supply, use is made of a DC power supply or an AC power supply or a power supply wherein the AC is superposed on the DC.
More specifically, one or more thin films of a semiconductor thin film such as polycrystalline silicon, single crystalline silicon, amorphous silicon, microcrystalline silicon, silicon germanium, silicon carbide, compound semiconductor (gallium arsenic, gallium phosphorus, gallium nitride, etc.), diamond, and diamond-like carbon (DLC), an insulator thin film such as silicon oxide, silicon oxide containing impurities (phosphosilicate glass (PSG), borosilicate glass (BSG), borophosphosilicate glass (BPSG), etc.), silicon nitride, silicon oxynitride, molybdenum oxide, titanium oxide, tantalum oxide, and aluminum oxide, an oxidative conductive thin film such as ruthenium oxide, indium oxide, indium tin oxide (ITO), iridium oxide, and palladium oxide, a metal thin film made by a refractory metal and conductive metal nitride thin film (tungsten, titanium, tantalum, molybdenum, tungsten nitride, titanium nitride, tantalum nitride, molybdenum nitride, etc.), silicide, copper, aluminum, aluminum-silicon or aluminum-silicon-copper, a high dielectric rate thin film such as BST, and the ferroelectric thin film such as PZT, PLZT, SBT, and BIT is formed.
Then, a silicon nitride film is formed by a gas containing hydrogen as the carrier gas and containing a silane-based gas such as monosilane, disilane, or trisilane as the material gas and ammonia, a silicon oxide film is formed by a gas containing hydrogen as the carrier gas and containing a silane-based gas such as monosilane, disilane, or trisilane as the material gas and an inert gas-diluted oxygen (for example argon- or helium-diluted oxygen) or an inert gas (for example argon- or helium-diluted ozone), and a polycrystalline silicon film is formed by a gas containing hydrogen as the carrier gas and containing at least one of monosilane, disilane, and trisilane as the material gas.
Note that, in the polycrystalline silicon film and the single crystalline silicon film, in order to control the carrier impurity concentration, phosphine, arsine and stibine are mixed into the silane-based gas containing monosilane, disilane, and trisilane in an appropriate amount to achieve an N-type, and diborane is mixed into the silane-based gas containing monosilane, disilane, and trisilane to achieve a P-type.
As the substrate, it is preferred to select it from among semiconductor or insulating materials including silicon, germanium, silicon germanium, silicon carbide, gallium arsenic, gallium aluminum arsenic, gallium phosphorus, indium phosphorus, zinc selenide, cadmium sulfide, quartz glass, borosilicate glass, aluminosilicate glass, and heat resistant resins.
Note that, preferably the thin film to be formed on the substrate includes a gate insulating film, and the gate insulating film is selected from among a silicon oxide film, silicon nitride film, silicon oxynitride film, aluminum nitride film, aluminum oxide film, tantalum oxide film, or composite films of the same.
The process of production of a thin film semiconductor device of the present invention is a method for producing a thin film semiconductor device containing a thin film layer by forming a thin film on a substrate in a vacuum chamber by catalytic CVD or high density CVD or high density catalytic CVD, characterized in that it comprises a cleaning step of feeding a carrier gas containing hydrogen to the vacuum chamber and cleaning the top of the substrate by the activated hydrogen H* generated in the carrier gas, a thin film forming step of forming a thin film on the substrate by feeding a material gas to the vacuum chamber, and a carrier gas stopping step of reducing or stopping the feed of the carrier gas, thin films being stacked on the substrate to form a thin film layer by repeating the cleaning step and the thin film forming step and the carrier gas stopping step or repeating the thin film forming step and the carrier gas stopping step after the cleaning step, and predetermined processing being applied to the thin film layer to fabricate a semiconductor element.
The process of production of a top gate type TFT of th e present invention is a method for producing a thin film semiconductor device containing a thin film layer by forming a thin film on a substrate in a vacuum chamber by catalytic CVD or high density CVD or high density catalytic CVD, characterized in that it comprises a cleaning step of feeding a carrier gas containing hydrogen to the vacuum chamber and cleaning the top of the substrate by the activated hydrogen H* generated in the carrier gas, a thin film forming step of forming a thin film on the substrate by feeding a material gas to the vacuum chamber, a carrier gas stopping step of reducing or stopping the feed of the carrier gas, and a step of forming a silicon film in at least the thin film semiconductor device forming region of the substrate and forming a thin film layer by forming at least a gate insulating film continuing from the silicon film by repeating the cleaning step and the thin film forming step and the carrier gas stopping step or repeating the thin film forming step and the carrier gas stopping step after the cleaning step to thereby form a thin film layer and applying predetermined processing to the thin film layer to thereby fabricate a top gate type TFT.
The process of production of a bottom gate type TFT of the present invention is a method for producing a thin film semiconductor device containing a thin film layer by forming a thin film on a substrate in a vacuum chamber by catalytic CVD or high density CVD or high density catalytic CVD, characterized in that it comprises a cleaning step of feeding a carrier gas containing hydrogen to the vacuum chamber and cleaning the top of the substrate by the activated hydrogen H* generated in the carrier gas, a thin film forming step of forming the thin film on the substrate by feeding a material gas to the vacuum chamber, a carrier gas stopping step of reducing or stopping the feed of the carrier gas, and a step of forming at least a gate insulating film in at least the thin film semiconductor device forming region of the substrate with the gate electrode formed in advance therein and forming a thin film layer by forming at least a silicon film continuing from the gate insulating film by repeating the cleaning step and the thin film forming step and the carrier gas stopping step or repeating the thin film forming step and the carrier gas stopping step after the cleaning step to thereby form a thin film layer and applying predetermined processing to the thin film layer to thereby fabricate a bottom gate type TFT.
The process of production of a dual gate type TFT of the present invention is a method for producing a thin film semiconductor device containing a thin film layer by forming a thin film on a substrate in a vacuum chamber by catalytic CVD or high density CVD or high density catalytic CVD, characterized in that it comprises a cleaning step of feeding a carrier gas containing hydrogen to the vacuum chamber and cleaning the top of the substrate by the activated hydrogen H* generated in the carrier gas, a thin film forming step of forming a thin film on the substrate by feeding a material gas to the vacuum chamber, a carrier gas stopping step of reducing or stopping the feed of the carrier gas, and a step of forming at least a first gate insulating film in at least the thin film semiconductor device forming region of the substrate with the first gate electrode formed in advance therein and forming a first thin film layer by forming at least a silicon film continuing from the first gate insulating film and forming a second thin film layer by forming at least a second gate insulating film for a second gate electrode continuing from the first thin film layer by repeating the cleaning step and the thin film forming step and the carrier gas stopping step or repeating the thin film forming step and the carrier gas stopping step after the cleaning step and applying predetermined processing to the first thin film layer and second thin film layer to thereby fabricate a dual gate type TFT.
In this way, in the methods, by the carrier gas stopping step of reducing or stopping the feed of the carrier gas, when forming various films, after the elapse of a predetermined time after the start of the film formation, the introduction of the carrier gas is reduced or stopped, therefore the ratio of the material gas becomes high in the vacuum chamber, the formation of the thin film onto the substrate is carried out at a high speed, and it becomes possible to improve the workability. Further, when forming a thin film on a substrate, since carrier gas containing hydrogen is fed, the activated hydrogen H* generated in the carrier gas cleans the substrate surface, thus a high quality thin film can be formed on the substrate. Further, by feeding hydrogen gas as the carrier gas, heating the thermal catalyst to a state enabling a catalytic action, and continuously forming at least the silicon film and the gate insulating film, a low stress and low contamination can be achieved in the gate channel portion.
Further, by applying predetermined processing to the high quality thin film layer obtained by these methods to fabricate a semiconductor element, so it becomes possible to obtain various thin film semiconductor devices of high quality.
Further, by employing a configuration wherein a step is formed in at least the semiconductor device forming region of the substrate and a single crystalline semiconductor film is grapho-epitaxially grown on the substrate containing the step or employing a configuration wherein the substance layer having a good lattice alignment with the single crystalline semiconductor is formed in at least the semiconductor device forming region of the substrate and the single crystalline semiconductor film is hetero-epitaxially grown on the substrate containing the substance layer, it is possible to obtain a single crystalline semiconductor film having a high electron mobility and excellent in operability.
Further, it is preferred to apply the thin film layer to the channel region, source region, or drain region of an insulating gate type electrolytic effect transistor and control the types of the impurities injected into these regions and/or concentrations thereof.
Further, according to the methods for producing a thin film semiconductor device, it is possible to produce a silicon semiconductor device, silicon semiconductor integrated circuit device, silicon-germanium semiconductor device, silicon-germanium semiconductor integrated circuit device, compound semiconductor device, compound semiconductor integrated circuit device, silicon carbide semiconductor device, silicon carbide semiconductor integrated circuit device, diamond semiconductor device, diamond semiconductor integrated circuit device, liquid crystal display device, electroluminescence display device, plasma display panel (PDP) device, light emission polymer display device, light emission diode display device, CCD area/linear sensor device, MOS sensor device, high dielectric/ferroelectric memory semiconductor device, high dielectric/ferroelectric memory semiconductor integrated circuit device, solar battery, and so on.